BX Leakback?

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rg
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BX Leakback?

Post by rg »

"Brothers and Sisters of The Fellowship of The Green Orb",
A BX turned up on my drive this morning, the car of a friend of a family, just "popping by" to pick up my eldest, hence no time to fiddle or take things off. The hydraulics low pressure light is taking around two minutes to turn off first thing in the morning, says the driver.
I had around ten minutes on this "ground stop" to do a quick check.
The pump cycles around every 60 secs, and the accumulator is less than a year old. The pump sounds fine.
The beastie rises and falls OK during Citaerobics, with the light coming on for around 45 secs when going from bottom to top. It rises quickly and smoothly.
So I would suspect a leak back from somewhere overnight. Are there any "favourites" with the BX? It has sat "tail-down" at rest for the three years I have known it (brake valve?), but the pressure problem is only recent.
(Ahh.. how refreshing to open the bonnet and have so much space compared with the XM 2.5....and the no-nonsense XUD chugging away..I could get to like one of these...)
rg
ghostrider
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BX Leakback?

Post by ghostrider »

rg, was the lhm level OK? I seem to remember mine having the same symptoms when the level was low, other possibility is a dirty filter in the reservoir preventing fluid getting to the pump quickly enough
Pete
________
HEMP MARIJUANA
Last edited by ghostrider on 22 Feb 2011, 05:48, edited 1 time in total.
rg
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Post by rg »

Ghostrider,
Thanks.
Yes, it's fine, both on the level indicator, and verified in the tank.
It goes up and down fine. The pump sounds good.
It has just passed through again, so I've done 10 or so more cycles of the suspension, so we will see if this has re-sealed something, or dislodged some crud.
Cheers
rg
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AndersDK
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Post by AndersDK »

The pump cycle of approx 60 seconds indicates no severe leaks - i.e. no leaks that would affect the pressure build up.
The fact that the pump (actually the regulator) is ticking at all - means the pump is fully capable of delivering the required upper pressure limit of approx 170bar - where the cut-out valve in the regulator emit's this tick sound.
This indicates that basically the pump is working OK - as pump failures are indicated by lack of pressure.
The pump may still have problems though - delivering adequate <font color="red"><i>volume</i></font id="red"> of pressure.
This may be due to these problems :
1) Pump intake (suction) hose leaking - taking in air. A very common problem on BX'es - as all BX'es are now at least 10y's old.
Telltales are the common deep craking on hose over the studs - or the hose showing lots of surface hairline cracks when bend. Quick test is replacing (preliminary) with 3/4" PVC water (garden) hosing.
2) Filter meshes in the reservoir clogged by dirt. It's known by most owners that the pump can deliver pressure in excess of 300bar (some 4000psi) - but very few are aware that the pump vey easily cavitates on the intake side - because of restriction on intake.
The pump simply starts working on vacuum - i.e. <font color="red"><i>nothing</i></font id="red"> - meaning neither oil or air is delivered from pump during part of the pump cycling.
3) The pump drive belt is slipping - due to a worn belt - or belt not tensioned correctly.
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Post by tomsheppard »

Anders is as usual likely to be right. Slipping belt or air leak on input side of pump look like the most likely problems. As the weather has been cold, THe belt may be slipping more than usual. The driver may report heavy steering early in the morning. That's a good clue.
rg
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Post by rg »

Thanks, folks,
The pump belt has around 8mm play in it, and I can't hear any squealing.
The damaged hose theory sounds good, along with the blocked filter.
rg
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Post by alan s »

Check on the colour of the LHM as a guide to how clean the rest of the system is.
If it's a yellowy brown, I'd suggest a drain, clean filters, a few new jubilee clips & a dose of hydraflush before doing it all over again & filling with new LHM.
Alan S
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DLM
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Post by DLM »

You COULD try the following:
(1) Run a few minutes, raising suspension to full height
(2) engine switch-off
(3) Open bonnet then lower height lever to lowest position
(4) Listening and observe (if you can manage it) at the reservoir.
Foamy LHM is a good clue to a pinholed feed pipe.
I did hear another suggestion: coat the outside of the feed pipe in a film of lhm and see if this shows signs of being pulled-in when the pump is running. A bit like a bicycle inner-tube puncture test in reverse.
rg
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Post by rg »

Thanks, folks, for all the kind advice,
The BX has just passed through again, and the driver reports that the fault has gone.
Maybe it was the Citaerobics?
rg
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